Frequently Asked Questions about Electric Convectors

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Frequently Asked Questions About Electric Convector Heaters – Answers from Practice

Electric convector heaters are among the most frequently purchased heating products on the Slovak market – and at the same time among those for which customers have the most questions. It's no wonder: a seemingly simple appliance that "just heats" turns out in practice to have a whole range of parameters, variants and uses. Over the years of working with these products, we have encountered hundreds of specific inquiries – and in this article we have gathered the ones that recur most often. The answers are specific, without unnecessary beating around the bush, and backed by real figures from practice.

What actually is an electric convector heater and how does it work?

An electric convector heater is a heating appliance that converts electrical energy into heat using a resistive element (heating element). Heat is transferred from the appliance to the room primarily by convection – that is, by air circulation. Cold air enters through the lower openings of the appliance, is heated near the heating element, and the warm air rises and leaves the convector through the upper grille. This creates a natural air circulation that evenly heats the entire room.

It is important to distinguish a convector heater from an electric oil-filled radiator: an oil radiator heats the air mainly by radiating heat from its surface, is heavy, takes a long time to heat up and a long time to cool down. A convector heater is lighter, reacts faster, and with properly set regulation can even be more economical – because it does not store thermal energy that it would then "shoot" into the room when you don't want it to.

What power output do I need for my convector heater?

This is by far the most common question. The basic rule found in every technical manual states 100 W per square meter of floor area for a standard, adequately insulated apartment or house. In practice, however, it's not that simple – this figure applies to rooms with a ceiling height of around 2.5 meters, with sufficient insulation of walls and windows at least in class U = 1.0 W/m²K.

Specific examples from real-world orders:

Children's room, 12 m² in a panel-building apartment, plastic window, no exterior wall → a Protherm 1000 (1000 W) is sufficient. The reserve is adequate, and the regulation takes care of the rest.
Living room, 20 m² in an older house with a plain wall facing north → at least a Protherm 2000 (2000 W), ideally with consideration of an additional heat source for freezing days.
Bathroom, 6 m² → a Protherm 500 (500 W) is the standard choice for an interior room without a window. With a north-facing window and an older apartment building, we increase to 750–1000 W.
Office, 15 m² in a new building with certified insulation → 1000 W is easily sufficient, and the convector will run at only 60–70% output most of the day.

A more detailed calculation methodology can be found in the article What power output of an electric convector heater do I need for my room in our Knowledge Center.

Is an electric convector heater expensive to run?

This is a question where it matters what you're comparing it to and how you use the convector heater. An electric convector heater has an efficiency of converting electrical energy into heat close to 100% – this is a physical fact. Every watt of electrical energy is converted into heat. From the point of view of the appliance itself, there are therefore no "wasted" losses.

The problem, however, lies in the price of electricity compared to, for example, natural gas or heat from a heat pump. In Slovakia in 2024, the price of electricity ranges from €0.18 to €0.25/kWh (depending on the tariff and distribution zone). If a convector heater has an output of 1500 W and runs for 8 hours a day, it consumes 12 kWh, which at a price of €0.20/kWh amounts to €2.40 per day. Over a heating season (180 days), that's €432 for just one room – a real amount that needs to be taken into account.

The key to savings is not the power output of the convector heater, but the quality of its regulation. A convector heater with a precise electronic thermostat that maintains temperature within ±0.5 °C consumes 15–25% less energy than a convector heater with a mechanical thermostat, where the temperature fluctuates by ±2–3 °C and the appliance cyclically overheats. That's why it's always worth considering the extra cost for better regulation when buying. You can find more on this topic in the article Convector heater with electronic vs. mechanical regulation: which is better.

Where can an electric convector heater be installed?

Electric convector heaters are essentially a universal solution – they can be installed almost anywhere there is an electrical connection. The most common scenarios from practice:

Apartments in panel buildings – a classic situation where central heating is either expensive or unreliable. The convector heater is mounted under the window and replaces or supplements the original radiators.
Cottages and garden houses – an ideal choice, since no complex installation is required. A socket or a fixed connection to the wiring is enough. In a cottage you visit only on weekends, you'll appreciate the weekly programmer function – the convector heater starts a few hours before your arrival and the house will be warm.
Offices and operational spaces – quick installation, simple operation, possibility of temporary relocation (if the convector heater has wheels).
Bathrooms – here, attention must be paid to the IP rating (degree of water protection). For bathrooms, at least IP21 is recommended, and for installation in so-called zones 2 and 3 (greater distance from the shower/bathtub), IP24. Always check the value in the technical data sheet.
Cellars and utility rooms – a convector heater also works well here, you just need to opt for a higher power output, since these spaces tend to be less well insulated.

What is not recommended, on the other hand, is installing a convector heater in places where it is covered by furniture or curtains. Blocking air flow dramatically reduces efficiency and can cause overheating. A very common mistake in practice is mounting a convector heater directly behind a long curtain that reaches the floor – in that case, the curtain gets heated, not the room.

Wall mounting or wheels – which is better?

This question has no clear-cut answer, because it depends on your specific use. Most customers choose wall mounting for permanent installation, where the convector heater serves as the primary heat source in a given room. The advantages are: the convector heater doesn't get in the way when cleaning, it can't tip over, it doesn't pick up dust from the floor as intensely, and it looks aesthetically cleaner.

The mobile version on wheels makes sense when you want to move the convector heater around – typically from the living room to the bedroom, or when you're not sure whether the placement is final. For Tesy brand appliances (and not only for them), a separate wheel set for Tesy is available, which allows a wall-mountable convector heater to be converted into a mobile appliance without any compromise in safety. You can find more about this decision in the article Wheels for an electric convector heater: when they're worth it and what to know.

The procedure for the wall mounting itself – from marking the position, through drilling, to connection – is described in detail in the article Mounting an electric convector heater on the wall: step-by-step procedure.

Can I leave the convector heater on all night?

Yes – and most modern convector heaters are specifically designed for continuous operation. They are equipped with thermal protection (thermistors), which automatically switch the appliance off in case of overheating. Standard electric convector heaters from reputable manufacturers (Protherm, Tesy, Noirot, Rointe and others) are certified for 24/7 operation.

What is not recommended is leaving the convector heater on at full power all night in the bedroom – not for safety reasons, but for comfort. The optimal sleeping temperature is 17–19 °C, and if you leave the thermostat set to 22 °C (the daytime comfort temperature), the bedroom may be unnecessarily hot, the air dry, and sleep of poor quality. The ideal solution is a convector heater with a weekly programmer, where you set a lower temperature for sleeping time (e.g. 17 °C) and an automatic rise back to 20 °C before your morning alarm.

Is it safe to have a convector heater in a children's room or around children?

Modern convector heaters are far more acceptable from a safety standpoint than old oil radiators or wood stoves. The surface of the convector heater's casing reaches a temperature of 50–70 °C during normal operation, which is unpleasant to touch but does not cause burns the way the hot glass of a stove does (150+ °C). In addition, most modern models have a protective grille preventing direct contact with the heating element.

For children's rooms, we recommend:

Wall mounting at a height of at least 15 cm above the floor (harder for a child to reach the grilles)
A model with a child lock on the control panel
Not covering the convector heater with blankets, clothing or toys
Not placing it in close proximity to a bed – at least 50 cm of free space

Why does my convector heater give off a smell? Is that normal?

When a new convector heater is switched on for the first time, a slight smell of burnt impurities and manufacturing dust can be noticed – this is normal and disappears completely after 1–2 hours of operation. Simply air out the room well.

If the smell appears later as well, the possible causes are:

Accumulated dust on the heating element – the most common reason. Dust settles on the warm surface of the heating element and burns off when it heats up again. Solution: regular cleaning. We describe the detailed procedure in the article Maintenance and cleaning of an electric convector heater: how to extend its lifespan.
Moisture inside the appliance – if the convector heater was out of use for a long time (for example, the whole summer) and was stored in a damp cellar, it may give off a musty smell when first switched on. Let it run at full power for 2–3 hours in a well-ventilated room.
Foreign objects inside – insects, a child's toy, or plastic packaging can get into the convector heater. Always check inside the grilles before the heating season.
Fault in the heating element – if the smell resembles burnt plastic or metallic sparks, disconnect the convector heater immediately and have it checked by a service technician.

Electric convector heater as the main or only a supplementary heat source?

This is one of the most important decisions when buying. An electric convector heater can, under the right conditions, function as a fully-fledged primary heating source – for example, in a well-insulated apartment, a cottage with low heat demand, or a room where central heating is unreliable or insufficient.

On the other hand, in an older family house with poor insulation, with large north-facing windows, where the temperature drops below −15 °C in January, an electric convector heater alone may be insufficient or financially disadvantageous. In such a case, it makes sense to use the convector heater as a supplementary source alongside a heat pump, gas boiler, or fireplace insert.

We discuss the topic of primary vs. supplementary heating in more detail in the article Electric convector heater as a main vs. supplementary heating source.

How to set the thermostat on a convector heater correctly?

Setting the thermostat correctly is more of an art than a science – and it directly affects consumption. Here are specific recommendations from practice:

Comfort temperature: 20–22 °C for occupied rooms (living room, office), 18–20 °C for bedrooms
Setback temperature (when you're not at home): 14–16 °C – it's not worth going lower, since heating a cold room back up to a comfortable temperature costs more energy than maintaining a mild setback temperature
Frost protection: 5–7 °C – the minimum temperature to prevent pipes from bursting (relevant mainly for cottages)
First startup: set the thermostat to maximum and observe at what temperature the convector heater switches off on its own. Then gradually lower the thermostat until you find the setting that maintains the desired temperature.

With convector heaters like the Protherm 1500 and other models with an electronic display, the setting is much more precise – you see the actual temperature in the room and set specific degrees Celsius, not just a numerical position of a dial.

Why does my convector heater blow air but not heat?

This complaint appears fairly often in practice – and usually has a simple cause. An electric convector heater (unlike a fan heater) does not have its own fan. Air flow occurs purely through natural convection. So if you feel "something blowing," it's air flowing through the grille by the force of convection itself – which is the correct function.

If the convector heater doesn't heat at all, the possible causes are:

The thermostat is set lower than the current room temperature (the convector heater has reached the target temperature and heating has stopped – everything is working correctly)
A cracked heating element – the convector heater switches on but doesn't produce heat
The fuse in the electrical distribution board has tripped
The child lock or control panel lock is active

Other typical faults and their solutions are described in detail in the article Common faults in electric convector heaters and how to fix them.

What's the difference between Protherm and Tesy convector heaters?

Both brands are well established on the Slovak market and offer reliable products, but they differ in several key aspects. Protherm (the electric convector heater series) is a traditional brand focused on simple operation and affordable prices. Tesy is a Bulgarian manufacturer that ranks among the European leaders in the electric convector heater segment – mainly thanks to more sophisticated electronic regulation, connectivity features (some models have Wi-Fi), and a wider range of products.

Specifically: if you're looking for a reliable and affordably priced convector heater for a cottage or as a backup heating source, the Protherm 1000 or Protherm 2000 is an excellent choice. If you're dealing with primary heating in an apartment where you want maximum savings and comfortable regulation, it's worth considering a Tesy with an electronic thermostat. You can find a detailed comparison in the article Protherm vs. Tesy electric convector heaters: what's the difference and which to choose.

Can I plug a convector heater into an extension cord?

This is a safety question with a clear answer: it depends on the type of extension cord. Standard extension cords for sockets are rated for a current of 10 A (2300 W) or 16 A (3680 W). A convector heater with an output of 2000 W draws a current of approximately 9 A – which is theoretically fine for a 10 A extension cord.

A problem arises if:

The extension cord has too small a wire cross-section (0.75 mm² – insufficient, the minimum is 1.5 mm² for a 2000 W load)
The extension cord is wound up on a reel – a coiled cable cools much less effectively and can overheat
Other appliances (chargers, TV, etc.) are also plugged into the same extension cord

Expert recommendation: for permanent installation, always use a fixed connection to a socket or a direct connection to the wiring. An extension cord is acceptable only temporarily, and only if fully unwound, properly rated (1.5 mm² cross-section), and with no other appliances on the same line.

How long does it take for a convector heater to warm up a room?

An electric convector heater reaches its operating temperature very quickly – the heating element heats up within 2–3 minutes of switching on. Warming up the room itself, however, is a longer process and depends on several factors:

Room volume: a room measuring 3 × 4 × 2.5 m has a volume of 30 m³. Heating it up by 10 °C requires roughly 10 × 30 × 0.335 kJ ≈ 100 kJ. A 1500 W convector heater can do this in under 2 minutes under ideal conditions – in practice (losses to walls, windows) it takes 15–30 minutes.
Heat losses of the room: in a poorly insulated room, reaching the target temperature can take significantly longer
Outdoor temperature: at −15 °C outside, losses are much higher than at +5 °C
Position of the convector heater: a convector heater placed on the floor under a window works more efficiently, because warm air rises and the cold draft from the window is captured immediately

Approximate times from practice: a well-insulated room of 12 m² + a 1000 W convector heater – heating from 15 to 21 °C takes about 20–30 minutes at an outdoor temperature of 0 °C. The same room at −10 °C outside with weaker insulation – 45–60 minutes.

Frequently Asked Questions (FAQ)

Can I use one convector heater for two connected rooms without a door between them?

Yes, but you must take into account the total area (and volume) of both rooms combined. For example, if you have an open kitchen and dining area with a total floor space of 28 m², you need a convector heater with an output of at least 2500–3000 W. A single 1500 W convector heater in such a space will struggle for every degree during frosty weather. A better solution may be a single powerful convector heater in a central location, or two smaller convector heaters – one in each part of the space.

Can I replace the heating element in a convector heater myself if it breaks?

Theoretically yes, if you have experience with electrical appliances – the heating element is usually modular and can be ordered as a spare part. In practice, however, we only recommend this to persons with electrical training or certification. An improperly replaced heating element can be a source of a short circuit or fire. Moreover, the warranty may become void after unauthorized opening of the appliance. Always contact the manufacturer's authorized service.

How many convector heaters can I connect to one electrical circuit?

This depends on the circuit's protection. A typical household circuit is protected by a 10 A or 16 A circuit breaker. On a circuit with a 16 A breaker, you can connect a load of a maximum of 16 × 230 = 3680 W. If you have two 1500 W Protherm convector heaters, their combined output is 3000 W – which is at the limit for one circuit. In practice, we recommend a separate electrical circuit for each convector heater with an output above 1500 W. Consult an electrician who can assess the condition of your home's wiring.

Is a convector heater suitable for allergy sufferers or people with respiratory problems?

An electric convector heater is a relatively suitable solution for allergy sufferers – unlike a hot-water fan convector or air conditioning, it has no filter that needs cleaning and in which mold could grow. It moves air slowly and naturally, without a strong air current that would stir up dust. The downside is that accumulated dust on the heating element burns off when heated and can temporarily worsen air quality – which is why regular cleaning of the grilles and the area around the heating element is important from a health perspective as well.

What does the "open window detection" function on some convector heaters mean?

This is a function for detecting an open window, found in more advanced electronic convector heaters (for example, higher-end Tesy models). If the room temperature drops quickly (which is typical when a window is open), the convector heater detects this and switches off for 15–30 minutes – so as not to heat the outdoors. After the window is closed and the temperature stabilizes, it automatically returns to normal mode. This function can save 5–10% of heating costs in households where windows are opened regularly.

Can I leave the convector heater switched on when I go on vacation?

If the convector heater is modern, certified, and has frost protection set (5–7 °C), you can leave it switched on at this temperature. In practice, customers do this regularly – especially with cottages and houses where pipes could freeze during a long absence combined with frost. Before leaving, always check that the convector heater is securely mounted, that there are no flammable materials nearby, and that the electrical wiring is in good condition. Never leave a convector heater switched on if it has a damaged cable or a burnt plug.

Conclusion

An electric convector heater is a simple but functional appliance – and most of the questions customers have stem from a misunderstanding of the basic principles of how it works, or from uncertainty when choosing the right model. We hope this overview of answers has helped clarify the most important aspects: from calculating power output, through safety, installation, regulation, to everyday use.

If you're looking for a specific product, take a look at the full range in the electric convector heaters category – you'll find models for various rooms and needs there, from the compact Protherm 500 to the powerful Protherm 2000. And for a more detailed comparison of individual criteria, we recommend the article How to choose an electric convector heater: power, regulation and other criteria in our Knowledge Center.

Have a question on this topic?

Not sure what to decide, or dealing with a specific situation in your household? Write to us - we're happy to help.